The present invention relates to an airbag device with a gas generator.
An airbag device installed in an automobile includes an airbag, a gas generator commonly called an inflator, and a module cover for covering the airbag. In an emergency of the automobile, such as when the automobile collides, the gas generator operates, causing the airbag to expand and to catch an occupant in the automobile.
FIG. 6 is a side view of an example of a conventional steering wheel; FIG. 7 is a front view of the conventional steering wheel; FIG. 8 is an enlarged sectional view taken along line 8xe2x80x948 of FIG. 7; and FIG. 9 is a sectional view of a gas generator incorporated in an airbag device of this steering wheel.
As shown in FIGS. 6 and 7, an airbag device 14 is installed in an area situated at the inner side of a steering wheel 10. Reference numerals 12 denote spokes.
As shown in FIG. 8, the airbag device 14 comprises a retainer 20 fixed on the steering wheel by a bracket 18, an airbag 22 including a gas-introducing-opening edge portion mounted to the retainer 20, a gas generator or inflator 24 mounted to the retainer 20 for ejecting gas into the airbag 22, and a module cover 26 for covering the airbag 22. The base end side of the module cover 26 is connected to the retainer 20.
As shown in FIG. 9, the gas generator 24 is formed of a container which comprises an outer-shell member and a cylindrical partition member 29, wherein the outer-shell member is formed by an upper housing 27 and a lower housing 28, and the cylindrical partition member 29 is installed inside the outer-shell member. One end of the partition member 29 passes through and protrudes downward from an opening in the bottom surface of the lower housing 28. The inner peripheral surface defining the opening and the outer peripheral surface of the partition member 29 are welded together by, for example, laser beam welding. An igniting agent or booster propellant 30 is held at the inner side of the partition member 29, whereas a gas generating agent or main propellant 32 is held at the outer peripheral side of the partition member 29.
A squib 34 is installed at the aforementioned one end of the partition member 29, and is constructed so that the igniting agent 30 is ignited when the squib 34 is energized through a squib connector 36 and a squib lead wire 38. When the igniting agent 30 is ignited, gas is ejected from openings 40 of the partition member 29, so that the gas generating agent 32 is ignited. As a result, a large amount of gas is generated rapidly. The gas passes through a filter 42 formed by mesh or the like, and is ejected outward from the gas generator 24 through openings 44, causing the airbag 22 to expand. When the airbag 22 expands, the module cover 26 cleaves along a tear line, causing the airbag 22 to expand greatly inside the vehicle. The steering wheel is secured by a nut 48 and an externally threaded portion 46 at the top end of a steering shaft.
In the above-described gas generator, when the gas generating agent is ignited, the internal pressure in the container increases, so that a large stress is exerted on a connection portion of the lower housing 28 and the partition member 29.
An object of the present invention is to provide a gas generator including a structure for fixing a partition member and a container, which can sufficiently resist a large stress when a gas generating agent is ignited as mentioned above, and to provide an airbag device including the gas generator.
Further objects and advantages of the invention will be apparent from the following description.
A gas generator of the present invention includes a container; a gas generating agent inside the container; and an igniter for igniting the gas generating agent. The container includes an outer-shell member and a partition member fixed to the outer-shell member, and at least a portion of the partition member is disposed inside the outer-shell member. A plurality of chambers for containing the gas generating agent is formed by the partition member. A fixation area increasing portion is provided at at least one of the partition member and the outer-shell member.
In such a gas generator, since the fixation area of the partition member and the container is large, it is possible to sufficiently resist a large stress even when it is exerted on a connection portion of the partition member and the container when the gas generating agent is ignited.
In the gas generator of the present invention, it is preferable that the partition member has a cylindrical shape, with one end thereof being fixed to an inside surface of the outer-shell member at one side of the outer-shell member, and the other end thereof passing through and extending outward from an opening provided at the other side of the outer-shell member. In addition, it is preferable that an inner peripheral surface defining the opening and an outer peripheral surface of the tubular partition member are fixed together. Further, it is preferable that the fixation area increasing portion is used to increase a fixation area of the inner peripheral surface defining the opening and the outer peripheral surface of the partition member. When the gas generator is constructed in this way, since the fixation area of the partition member and the opening of the outer-shell member is large, gas leakage does not occur even when a large gas pressure is exerted on the fixation portion.
In this case, it is preferable that the fixation area increasing portion is an annular portion provided at the outer-shell member and protruding inside the outer-shell member. When the gas generator is constructed in this way, the annular portion is pushed against the outer peripheral surface of the partition member when the outer-shell member expands outward by the gas pressure as a result of ignition of the gas generating agent. Therefore, the connection between the outer-shell member and the partition member is made stronger, and gas leaks from a portion between these members is more reliably prevented.
In the present invention, it is preferable to fix the opening of the outer-shell member and the partition member by welding. In such a case, it is possible to considerably increase the weld strength between the partition member and the outer-shell member by increasing the welding depth, and to considerably reliably prevent gas leak from the portion between the partition member and the outer-shell member.
An airbag device of the present invention includes an airbag; any one of the above-described gas generators for generating gas to expand the airbag; and a module cover for covering the airbag.